commit 91c43da924dec2afa7e4bcb8df456493122e9ec7
author Dimitry Ivanov <dimitry@google.com> Mon Feb 29 13:21:43 2016 -0800
committer Dimitry Ivanov <dimitry@google.com> Mon Feb 29 13:21:43 2016 -0800
tree 1cdcfdbf72fa74dda38841ccb21031aa852cb20d
parent e1f84475c177a2d81b40b25331935a09a1fcd92f

Fix locking of libnativeloader

This commit fixes race condition introduced in
d047c925af62e1fe28fcd1c1940df4afe18d458a

Bug: http://b/27189432
Bug: http://b/22548808
Change-Id: I5d94f130937f18d3443878b3521715a8f87427e0

libnativeloader/native_loader.cpp

diff --git a/libnativeloader/native_loader.cpp b/libnativeloader/native_loader.cpp
index 837924b..ce893db 100644
--- a/libnativeloader/native_loader.cpp
+++ b/libnativeloader/native_loader.cpp
@@ -80,8 +80,6 @@
       return nullptr;
     }
 
-    std::lock_guard<std::mutex> guard(mutex_);
-
     android_namespace_t* ns = FindNamespaceByClassLoader(env, class_loader);
 
     LOG_FATAL_IF(ns != nullptr, "There is already a namespace associated with this classloader");
@@ -142,12 +140,12 @@
   }
 
   bool initialized_;
-  std::mutex mutex_;
   std::vector<std::pair<jweak, android_namespace_t*>> namespaces_;
 
   DISALLOW_COPY_AND_ASSIGN(LibraryNamespaces);
 };
 
+static std::mutex g_namespaces_mutex;
 static LibraryNamespaces* g_namespaces = new LibraryNamespaces;
 
 static bool namespaces_enabled(uint32_t target_sdk_version) {
@@ -157,6 +155,7 @@
 
 void PreloadPublicNativeLibraries() {
 #if defined(__ANDROID__)
+  std::lock_guard<std::mutex> guard(g_namespaces_mutex);
   g_namespaces->PreloadPublicLibraries();
 #endif
 }
@@ -173,6 +172,7 @@
     return nullptr;
   }
 
+  std::lock_guard<std::mutex> guard(g_namespaces_mutex);
   android_namespace_t* ns = g_namespaces->Create(env,
                                                  class_loader,
                                                  is_shared,
@@ -199,6 +199,7 @@
     return dlopen(path, RTLD_NOW);
   }
 
+  std::lock_guard<std::mutex> guard(g_namespaces_mutex);
   android_namespace_t* ns = g_namespaces->FindNamespaceByClassLoader(env, class_loader);
 
   if (ns == nullptr) {
@@ -223,6 +224,7 @@
 
 #if defined(__ANDROID__)
 android_namespace_t* FindNamespaceByClassLoader(JNIEnv* env, jobject class_loader) {
+  std::lock_guard<std::mutex> guard(g_namespaces_mutex);
   return g_namespaces->FindNamespaceByClassLoader(env, class_loader);
 }
 #endif